Residents of America’s biggest cities are struggling to book vaccine appointments because of the rising wave of the Omicron coronavirus variant and a rush in demand for booster shots before Christmas.

Walgreens, one of the country’s biggest pharmacy chains by number of pharmacists, says it is observing record levels of demand, while those looking to book appointments in some localities are having to wait as long as two weeks.

The jostle for vaccine appointments, especially in big cities, has drawn comparisons with a year ago when the Trump administration initially struggled to funnel doses to those who needed them when cases were surging in the runup to Christmas.

Experts warn that the lack of appointments in some regions will mean the heavily mutated new strain will spread more quickly in the US than it has in the UK, where daily cases are at record levels.

Eric Topol, director of the Scripps Research Translational Institute, said: “We don’t have the capability to deliver vaccines across the country rapidly, and we are relying heavily on people getting appointments at pharmacies.”

He added: “This is just one of several reasons we are very underprepared for the onslaught of Omicron. ”

US president Joe Biden has urged Americans to get booster shots as Omicron begins to spread. Anthony Fauci, the president’s chief medical adviser, said this week that booster shots of both BioNTech/Pfizer and Moderna’s vaccines would offer considerable protection against the new variant, which has swept through South Africa and is now doing the same in the UK and Denmark.

Vaccination rates in the US have begun to pick up, though they lag far behind some European countries. In the UK, 43 per cent of all over-12s have received a booster dose, according to the latest government figures. In the US, the figure is 30 per cent of all fully vaccinated over-18s.